Nowadays, display products mostly use a backlight system as a light source for displaying images. The display products are, for example, liquid crystal displays, digital photo frames, e-book readers, mobile terminals, vehicle display screens and stereoscopic displays.
Among them, Liquid Crystal Display (LCD) used as a display device has become the mainstream in the field of flat panel displays. The display of LCD is realized by an electric field formed by two pieces of conductive glass driving liquid crystals therebetween. Since liquid crystal itself does not emit light, the LCD needs an external light source to achieve transmissive or reflective display. Most existing LCDs are transmission type, for which the backlight module is an indispensable part.